Thermally insulated enclosure containing equipment intended to operate at a temperature below 0°c

ABSTRACT

Insulated enclosure having at least one surface that is planar, containing at least one piece of equipment intended to operate at a temperature below 0° C., the interior space of the enclosure being intended to be at a pressure below atmospheric pressure and being filled with thermal insulation, and the thermal insulation being made up of a multitude of spherical beads made of thermally insulating material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority wider 35 U.S.C. § 119(a) and (b) to French patent application No. FR1905376, filed May 22,2019, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a thermally insulated enclosurecontaining equipment intended to operate at a temperature below 0° C.,or even at a cryogenic temperature that is at least below −54° C.

BACKGROUND OF THE INVENTION

Such enclosures are used to insulate a cryogenic distillation column.Usually, the enclosure is filled with perlite, but in order to improvethe thermal insulation it is known practice to apply a vacuum to theperlite-filled enclosure, in order to improve the insulation.Vacuum-packed perlite is a conventional high-performance thermalinsulator used in cryogenic storage facilities or else in cold boxes ofcryogenic gas separation units.

The outer shell of the storage facility or of the cold box, which isessentially cylindrical or spherical in shape, is mechanicallydimensioned to withstand the vacuum, as a reverse pressure, therebyrequiring a thick wall that is expensive and heavy.

The shape of the enclosure, having neither edges nor corners, isdictated by the need to improve the resistance to external pressure. Asnoted in FR2695714, a vacuum insulated distillation column is, bydefinition, placed inside a cylindrical enclosure. A cylindricalenclosure generally has ends which are either hemispherical orsemi-ellipsoidal.

Now, the parallelepipedal shape generally used when the thermalinsulation is not under vacuum offers a number of advantages,particularly the greater ease of holding it in place for transport and abetter level of filling when a container is used for transport, or elsewhen the equipment, typically heat exchangers of the brazed aluminiumplate type, are parallelepipedal in shape.

When a vacuum is applied to an enclosure of parallelepipedal shape, thewalls that form the enclosure are mechanically unable to withstand thevacuum with a wall of small thickness.

In addition, when use is made of perlite in pulverulent form, it has thedisadvantage of settling down when the vacuum is applied. The expandedperlite usually employed for thermally insulating enclosures has anuneven shape and may break when subjected to too high a pressure.

According to the prior art, an outer shell of cylindrical or sphericalshape is dimensioned to be able to mechanically withstand the vacuum(namely to withstand the atmospheric pressure of 1 bara applied to itsexterior face): that requires a considerable wall thickness, because ofthe reverse pressure, often combined with the use of reinforcing hoops.Filling is achieved via an orifice in the enclosure, then vacuum isapplied, then the vacuum to is broken by introducing perlite via theorifice. Thus, several cycles of “applying a vacuum/breaking the vacuumwith the addition of perlite” are thus conducted until the perlite isproperly settled and the outer shell is properly filled. The finalvacuum is then applied, typically of around 10⁻¹ to 10⁻³ mbara, so as toensure high-performance thermal insulation of the cryogenic storagefacility or of the cold box.

SUMMARY OF THE INVENTION

One subject of the invention provides a thermally insulated enclosurehaving at least one surface that is planar, preferably all the surfacesbeing planar, containing at least one piece of equipment intended tooperate at a temperature below 0° C., or even at cryogenic temperature,the interior space of the enclosure being intended to be at a pressurebelow atmospheric pressure and being filled, preferably completelyfilled, with thermal insulation and the thermal insulation being madeup, in respect of at least three-quarters of the volume thereof, of amultitude of spherical beads made of thermally insulating material andwhich are possibly hollow, having a diameter of at most 1 mm and havinga crush strength such that the volume of the entity formed by themultitude of beads would reduce by at most 10%, or even 5%, preferablyby at most 1%, if the entity made up of the multitude of beads weresubjected to a pressure of 0.1 MPa.

According to other optional aspects:

-   -   the walls of the enclosure are not thick enough to withstand the        vacuum if the insulation had a crush strength such that its        volume would reduce by more than 10%, or even 5%, or if        appropriate by more than 1% if the enclosure were evacuated to a        pressure below 10⁻¹ mbara;    -   the enclosure is parallelepipedal in shape;    -   the beads are made of glass and/or of perlite and/or of        vermiculite;    -   the enclosure has a minimum volume of 12 m³;    -   the enclosure consists of a container which is a        parallelepipedal metal box of standardized dimensions designed        for transporting goods, equipped at least at one corner with a        grab component allowing it to be lashed down and transhipped;    -   the equipment comprises or is at least one column intended to        perform an exchange of heat and/or of material and/or at least        one heat exchanger and/or at least one storage facility and/or        at least one phase separator; and/or    -   the equipment is a column or a heat exchanger, the equipment        being of parallelepipedal shape.

Another aspect of the invention provides a method for filling anenclosure as described hereinabove, wherein at least one item ofequipment is placed inside the enclosure, the enclosure is filled withthe multitude of beads, the enclosure is closed and at least partiallyevacuated, preferably in a single evacuation step.

Preferably, the enclosure is filled with beads through an opening formedby removing a sheet metal panel that forms part of a wall of theenclosure or that constitutes a wall of the enclosure.

Another aspect of the invention provides a method of separation at atemperature below 0° C. using distillation and/or scrubbing, using aninsulated enclosure of parallelepipedal shape containing at least onepiece of equipment, the interior space of the enclosure being intendedto be at a pressure below atmospheric pressure and being filled withthermal insulation, the thermal insulation being made up, in respect ofat least three-quarters of the volume thereof, of a multitude ofspherical beads made of thermally insulating material and which arepossibly hollow, having a diameter of at most 1 mm and having a crushstrength such that the volume of the entity formed by the multitude ofbeads would reduce by at most 10%, or even 5%, preferably by at most 1%,if the entity made up of the multitude of beads were subjected to apressure of 0.1 MPa, wherein the equipment performing the separationoperates at a temperature below 0° C., or even at cryogenic temperature,and at a preferably above-atmospheric pressure, and the space filledwith insulation is evacuated to a pressure below atmospheric pressure,preferably below 10⁻¹ mbara.

The volume of the entity formed by the multitude of beads would reduceby at most 10%, or even 5%, preferably by at most 1% if the entityformed by the multitude of beads were subjected to a pressure of 0.1MPa; that means that, for a multitude of beads already at atmosphericpressure, if they were subjected to an additional pressure of 0.1 MPa,the reduction in volume observed would, at the very most, be thatclaimed.

Certain embodiments of the invention offer amongst others the advantagesof reducing the time and cost involved in installing the insulatedenclosure, of reducing the mass of the enclosure, and of avoidingproblems of deformation of the enclosure.

Certain embodiments of the invention can include use of an enclosure ofparallelepipedal shape, the thermal insulation of which is able towithstand atmospheric pressure when under vacuum. Certain embodiments ofthe method of manufacture can include completely filling the outer shellwith a pulverulent material in the form of spherical or near-sphericalbeads, preferably under gravity. The outer shell is then evacuated.

Because the material in the form of spherical beads is only slightlycompressible, this material is able to withstand the mechanical forceassociated with the vacuum, while at the same time pressing against theinternal equipment inside the outer shell (internal storage facility,distillation column, exchanger, piping, separator vessel, valves, etc.)without deformation of the wall of the outer shell: in this way,deformation of the outer shell is avoided. The outer shell can thereforebe simplified to a simple fluidtight “skin” which contains thepulverulent material in order to control the insulation distances beforethe vacuum is applied.

The fluidtight outer shell is not dimensioned to mechanically withstandthe vacuum (namely to withstand the atmospheric pressure of 1 barapplied to its exterior face). The pressure forces will pass through theinsulation, thanks to the use of a pulverulent material that isincompressible or only slightly compressible (namely of which themechanical compression strength is higher than the mechanical force tobe transmitted), typically glass beads (for example, the product K1 from3M®) or perlite, or else vermiculite.

The beads used have a diameter less than 1 mm, or preferably than 800microns or than 600 microns, or even than 500 or than 120 microns. Thebeads used preferably have a diameter greater than 10 microns, or evengreater than 100 microns. They may be hollow.

The enclosure is filled by tipping the beads through an opening, itbeing possible for the enclosure to be lying down or upright. Thisopening may be formed by removing a sheet metal panel that forms part ofa wall of the enclosure or that constitutes a wall of the enclosure, forexample the roof. Otherwise, an opening may be formed in the outer shellof the enclosure in order to allow the beads to be installed therein.

The outer shell is completely filled with beads, essentially under theeffect of gravity. Vibration, or else tapping on the wall, for exampleusing a hammer or a mallet, may also be used to help the beads to flowinto all of the regions of the outer shell, namely including the lessaccessible or “hidden” regions such as underneath a support or piping,and limit the heaping effect. The outer shell may be “tilted” so thatall of the “empty” volume is correctly filled under the effect ofgravity, by placing it in different positions.

The outer shell of small thickness may have a certain rigidity in orderto maintain a controlled geometric appearance during the filling withthe pulverulent insulating material, so as to ensure the correctdistances of insulation with respect to the internal equipment. It isalso possible to provide local supports or spacers in order to containthe material dimensionally during filling.

Once the enclosure is filled to the brim, it is closed. This can be doneby replacing the removed sheet metal panel mentioned earlier. Otherwise,a lid, typically planar, which may be a simple welded sheet metal panel,may be attached over the top of the opening in a fluidtight manner. Thesheet metal panel or the lid is preferably incapable of withstanding thevacuum (namely the atmospheric pressure of 1 bara) and will thereforeneed to rest on the beads in order to avoid any unacceptable deformationduring the evacuation of the enclosure, the sheet metal panel or the lidthus forming part of the shell. Alternatively, filling is performedthrough a filling orifice which is then closed off by a blind flange.

Once the enclosure is closed, the single operation of applying the finalvacuum, typically of around 10⁻¹ to 10⁻³ mbara can be performed in orderto ensure high-performance thermal insulation of the cryogenic storagefacility or of the cold box, without having to top up with insulatingproduct and without fear of deforming the small-thickness walls, thepressure forces being absorbed by the insulation, while pressing againstthe internal equipment inside the outer shell (internal storagefacility, distillation column, exchanger, piping, separator vessel,valves, etc.).

The collection of spherical beads with which the enclosure is filled hasa crush strength such that its volume would reduce by at most 10%, oreven 5%, preferably by at most 1%, if the beads were subjected to apressure of 0.1 MPa, namely typically the pressure experienced if theenclosure is evacuated to a pressure below 10⁻¹ mbara, and assuming thatthe shell contributes no mechanical strength.

-   -   For all applications, there is a saving on material for the        outer shell (smaller thickness) and a saving in evacuation with        just one vacuum-pulling step.    -   For a distillation unit for which distillation takes place at at        least one temperature below 0° C., or even at cryogenic        temperature involving a distillation column and/or a heat        exchanger which is/are contained in a parallelepipedal cold box        or else in a simple container, for example a container having        the standardized dimensions rendered fluidtight.    -   For a cryogenic storage facility for which the inside of the        storage facility is at a temperature below 0° C., or even at        cryogenic temperature in which a gas or liquid reservoir is        contained inside an insulated enclosure of parallelepipedal        shape that may be a container to standardized dimensions.    -   A lorry carrying a cryogenic storage facility as described        hereinabove.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become apparentfrom the to description hereinafter of embodiments, which are given byway of illustration but without any limitation, the description beinggiven in relation with the following attached FIGURE:

The FIGURE illustrates an air separation unit employing cryogenicdistillation, comprising several insulated enclosures.

DETAILED DESCRIPTION OF THE INVENTION

A first insulated enclosure CB1 of parallelepipedal shape contains anair distillation column C, which in this instance is cylindrical butcould have other geometries. The enclosure CB1 has a volume of at least12 m³ and also contains a subcooler SR and pipes D3 to facilitate thedrawing of the vacuum. The space around the equipment of the column isat least three-quarters filled, and preferably completely filled, with amultitude of spherical beads made from a thermally insulating material,and which are possibly hollow, having a crush strength preferably suchthat their volume would reduce by at most 10%, or even 5%, preferably byat most 1%, if the enclosure were evacuated to a pressure of 0.1 MPa.

The first enclosure CB1 is a parallelepipedal metal box of standardizeddimensions designed for transporting goods, equipped at least at onecorner with a grab component allowing it to be lashed down andtransshipped.

The first enclosure CB1 may contain a main heat exchanger for coolingthe air intended for the column and a distributor D3 which facilitatethe drawing of the vacuum.

A second insulated enclosure CB2 contains a condenser R and distributorsD1, D2 which facilitate the drawing of the vacuum.

A third insulated enclosure CB3 contains filters F which filter a liquidcoming from the column C heading towards the pump P and a distributor D4which facilitate the drawing of the vacuum.

The unit may comprise another insulated enclosure containing only themain heat exchanger, the insulation being in the form of beads.

The air distillation column C intended to operate at a pressure higherthan atmospheric pressure is placed in the parallelepipedal enclosureCB1, for example a container of standardized dimensions. Thedistillation column C is attached to pipework for supplying it with air,for transferring potential reflux liquids and for transporting theproducts of the distillation. The enclosure CB1 is arranged with a largeopening on one wall. One wall the may even be completely open. Theenclosure is filled with beads until it is completely full, and theenclosure is agitated to compact the beads closely together. The beadsused may for example be K1 glass microspheres made by 3M®, having adensity of 0.125 g/cm³. The wall is closed again for example by weldingthe wall or part of the wall in place, and the enclosure is evacuateddown to a pressure of below 1 bara, typically a pressure of below 10⁴mbara, or even of below 10⁻³ mbara.

It is possible for the enclosure CB1 to contain thermal insulators otherthan the beads. For example, instrumentation or supports situated insidethe enclosure may be insulated using Durostone® Epoxy EPM203 or an itemof equipment in the enclosure may be covered with a layer of insulation,the thermal insulation used having compression properties at leastequivalent to those of the beads. Nevertheless, the beads willthemselves alone constitute at least three-quarters of the insulation interms of volume.

In the example, the enclosure has an outer shell containing equipmentwhich is for example a column. It is also possible for the equipment toconsist of a parallelepipedal box itself containing a column or a heatexchanger. In that case, the space between the parallelepipedal box andthe outer shell is filled with a multitude of spherical beads made froma thermally insulating material, and which are possibly hollow, having acrush strength preferably such that their volume would reduce by at most10%, or even 5%, preferably by at most 1%, if the entity formed by themultitude of beads were subjected to a pressure of 0.1 MPa.

The space between the parallelepipedal box and the column does notcontain insulation and is not evacuated. The space between theparallelepipedal box and the outer shell is filled by removing a sheetmetal panel that forms part of a wall of the enclosure or thatconstitutes a wall of the enclosure, for example the roof. Otherwise, alid may be used, as mentioned hereinabove.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims. The presentinvention may suitably comprise, consist or consist essentially of theelements disclosed and may be practiced in the absence of an element notdisclosed. Furthermore, if there is language referring to order, such asfirst and second, it should be understood in an exemplary sense and notin a limiting sense. For example, it can be recognized by those skilledin the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means thesubsequently identified claim elements are a nonexclusive listing (i.e.,anything else may be additionally included and remain within the scopeof “comprising”). “Comprising” as used herein may be replaced by themore limited transitional terms “consisting essentially of” and“consisting of” unless otherwise indicated herein.

“Providing” in a claim is defined to mean furnishing, supplying, makingavailable, or preparing something. The step may be performed by anyactor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event orcircumstances may or may not occur. The description includes instanceswhere the event or circumstance occurs and instances where it does notoccur.

Ranges may be expressed herein as from about one particular value,and/or to about another particular value. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value and/or to the other particular value, along withall combinations within said range.

1. A thermally insulated enclosure having an interior space, thethermally insulated enclosure comprising: at least one outer surfacethat is planar; at least one piece of equipment (C, SR) intended tooperate at a temperature below 0° C. disposed entirely within theinterior space of the thermally insulated enclosure; wherein theinterior space of the enclosure is configured to operate at a pressurebelow atmospheric pressure and be at least partially filled with thermalinsulation, wherein the thermal insulation comprises, in respect of atleast three-quarters of a volume of the interior space, a multitude ofspherical beads made of thermally insulating material and which arehollow, wherein the spherical beads have a diameter of at most 1 mm andhave a crush strength such that the volume of an entity formed by themultitude of spherical beads would reduce by at most 10% when the entitymade up of the multitude of beads are subjected to a pressure of 0.1MPa.
 2. The thermally insulated enclosure according to claim 1, of whichthe walls are not thick enough to withstand the vacuum if the insulatorhad a crush strength such that its volume would reduce by more than 10%when the enclosure was evacuated to a pressure below 10⁻¹ mbara.
 3. Thethermally insulated enclosure according to claim 1, of parallelepipedalshape.
 4. The thermally insulated enclosure according to claim 1, inwhich the spherical beads are made of glass.
 5. The thermally insulatedenclosure according to claim 1, having a minimum volume of 12 m³.
 6. Thethermally insulated enclosure according to claim 1, wherein theenclosure comprises a container that is a parallelepipedal metal box ofstandardized dimensions designed for transporting goods, equipped atleast at one corner with a grab component allowing the enclosure to belashed down and transshipped.
 7. The thermally insulated enclosureaccording to claim 1, wherein the equipment is selected from the groupconsisting of at least one column configured to perform an exchange ofheat and/or of material, at least one heat exchanger, at least onestorage facility, at least one phase separator, and combinationsthereof.
 8. The thermally insulated enclosure according to claim 7,wherein the equipment is a column (C) or a heat exchanger (SR), theequipment being of parallelepipedal shape.
 9. A method for filling thethermally insulated enclosure according to claim 1, the methodcomprising the steps of: placing at least one item of equipment insidethe enclosure; filling the enclosure with the multitude of sphericalbeads; closing the enclosure; and at least partially evacuating theinterior space inside the enclosure.
 10. The method according to claim9, wherein the enclosure is filled with the spherical beads through anopening formed by removing a sheet metal panel that forms part of a wallof the enclosure or that constitutes a wall of the enclosure.
 11. Amethod of separation at a temperature below 0° C. by distillation and/orscrubbing, using the thermally insulated enclosure according to claim 1,wherein the interior space is filled with insulation and is evacuated toa pressure below atmospheric pressure.